This invention relates generally to a novel art form in which a sculptured object appears optically to be embedded in a transparent block, and specifically to a sculptured art form including a transparent block of material having an index of refraction such as to produce internal reflection at one wall of the block, the internal reflecting wall having a cavity formed therein representative of one-half of an object to be viewed.
In present day techniques involving certain art forms, it is known to embed an object to be viewed in a transparent medium. Acrylic polymers and glass as art forms have been used for completely embedding such a three-dimensional object within the transparent material. This art form involves taking a fully formed object and submerging and suspending the object within the molten transparent material until the material has hardened.
The present invention utilizes a transparent block having a sculptured cavity in one wall and internal light ray reflectance that optically projects the image of the sculptured cavity such that the cavity appears to be a fully formed three-dimensional object embedded in the block.
When a light ray traverse from a more dense medium to a less dense medium, the light ray is said to be refracted at the interface or wall between the two media. The angle between the normal to the wall surface that the light ray strikes and the wall surface is called the angle of incidence while the angle of the light ray emerging from the more dense medium relative to a normal to the wall surface is called the angle of refraction. Under Snell's law, the ratio of the sin of the angle of incidence to the sin of the angle of refraction is a constant. When a light ray traverses from a more dense medium to one of less density, as the angle of incidence becomes greater, so does the angle of refraction. Increasing the angle of incidence results in reaching a particular angle where the refracted ray becomes tangent to the wall interface between the two media. This is called the critical angle. Increasing the angle of incidence above the critical angle will result in total internal light reflection within the more dense medium. It has been determined that transparent acrylic polymers, known under the trademarks PLEXIGLASS or LUCITE, have indicies of refraction of 1.491, very close to that of some glass. This produces a critical angle of around 43 degrees for the acrylic polymer.
The image of a point source light formed by a plane mirror lies on the normal to the mirror surface and is as far back behind the mirror optically as the point source is in front of the mirror. As image formed by light rays which do not actually originate from the viewed object but appear to do so, are called virtual images. In most cases, an object forms an image as a three-dimensional object when viewed in a plane mirror. Since for every point source of light on an object there corresponds a similar point source in its image when mirrored, the image appears three-dimensional also. In the present invention, a cavity formed on the interface wall of a transparent block that exhibits internal reflectance acts as the source of both a real and a virtual image. Optically, the cavity is viewed as a complete three-dimensional object if the cavity is formed as a symmetrical one-half of the object viewed. Moreover, the adjacent block walls may be angularly disposed relative to each other to provide multiple internal reflection such that when viewed through certain walls, the object formed by the cavity appears to be fully embedded inside the block.
In accordance with the instant invention, transparent blocks of an acrylic polymer are selected such that an observer can readily perceive one wall of the block as having internal light reflection. The symmetrical one-half of an object cavity is sculptured in one wall that is observed to have internal reflection.